Endometrial cancer is the most common gynecological malignancy in the United States, with 68 percent to 83 percent of women (treated with adjuvant vaginal brachytherapy (VBT) for Stage II or III) surviving 5-years. Vaginal stenosis or shortening may occur in up to 65 percent of patients treated with VBT and interfere with normal sexual function. This R21 pilot study will provide preliminary data on the feasibility of recruiting women to participate in a trial of vaginal dilator use (an instrument used to break up adhesions in the vagina after VBT) and test a method to increase compliance with the intervention. Feasibility and compliance are necessary prerequisites to future studies of the effectiveness of vaginal dilators in maintaining vaginal length post VBT and possibly sexual health. This study will also provide effect size calculations for a larger randomized trial of the use of vaginal dilators to maintain vaginal length after VBT. It is imperative to study vaginal dilatation after VBT since it is an invasive, long-term intervention that is a common recommended practice, but is based on little empirical evidence. The findings of the proposed study would provide the groundwork for future research that could have clinical implications for behavioral and device interventions to maintain sexual health after cancer therapy. The preliminary data from this study will inform future research in one of two ways: 1) if this study indicates that the intervention is feasible, the next trial will assess the association between prescribed dilator use and vaginal length and will further assess the association between vaginal length and sexual function post VBT;2) if the preliminary data identifies feasibility problems, especially in the area of adherence to the intervention, then this study will inform a future trial of alternate methods to address protocol adherence. While this R21 and the subsequent work will focus on endometrial cancer, the methodology will be useful in continuing the principal investigator's program of research in sexual function after VBT or pelvic radiotherapy (RT) for both gynecologic malignancies and other malignancies that require pelvic RT such as rectal or bladder cancer. PUBLIC HEALTH RELEVANCE: Endometrial cancer is the most common gynecological malignancy in the United States, with 68 percent to 83 percent of women (treated with adjuvant vaginal brachytherapy (VBT) for Stage II or III) surviving 5-years. Vaginal stenosis or shortening may occur in up to 65 percent of patients treated with VBT and interfere with normal sexual function. This R21 pilot study will provide preliminary data on the feasibility of recruiting women to participate in a trial of vaginal dilator use (an instrument used to break up adhesions in the vagina after VBT) and test a method to increase compliance with the intervention, both of which are necessary prerequisites to future studies of the effectiveness of vaginal dilators in maintaining vaginal length and helping maintain sexual health after VBT.